The Lightweight Multi-objective Optimization Design Of The Bus Body Based On Modular And Multi-cell Structures

Since the reform and opening up policy implemented the economic development rapidly in China, what also the exchanges between cities, rural and urban areas become more and more frequent, and the "twelfth five-year" about the urbanization construction, highway construction and development of city bus, make the highway passenger quantity and mileage continue to grow. These provide a basis for the rapid growth of passenger cars. However, with the rapid development of passenger car industry and the increasing of bus-owned, frequently traffic accidents make the passenger safety increasingly bring to the attention of the passengers and passenger car manufacturers. In addition, according to the survey, vehicle exhaust has become one of the major source of atmospheric pollutants, vehicle emissions make the problem of air pollution become worse and worse. So as the leading role of public transportation passenger car needs to play a bigger role in energy conservation and emissions reduction. Study showed that lightweight has great significance in saving the cost of passenger bus body manufacture, reducing energy consumption and the exhaust emission. However, bus body lightweight has important effect on the safety of the whole car body, and both often conflicting and contradictory. This thesis is aimed at researching the lightweight of the passenger car by multi-objective optimization study of the modular and cellular structure bus body. In this paper, the research contents mainly revolve around the following aspects:First of all, to establish a finite element model of bus body, and the bus body structure mechanic performance analysis was done with the help of numerical simulation method, found that the local stress concentration significantly, stiffness safety margin is bigger, rollover safety seriously insufficient, and redundant structure various lead to excessive body quality in the original body structure, which mean that the original bus body structure has a larger optimization design space. Secondly, modular design of bus body and then reconstruct module and structure optimization design of bus body based on the sensitivity coefficient of each sub-block thickness to the bus body torsional stiffness, this method not only achieve the goal of the lightweight design, also improve the performance of the bus body structure strength. Then, this paper proposes a new kind of pane cell structure, and studies its crashworthiness and bending and the application in passenger bus body. Research results showed that the new kind of pane cell structure has excellent crashworthiness and flex resistance, its application in bus body reduce the bus body weight and improve the rollover safety performance of bus body. In the end, the article further conducted the multi-objective optimization design aimed at lightweight and rollover safety body based on the above research, and through the multi-objective optimization design is further strengthened the side of the bus body safety performance, realize the effect of lightweight bus body design. Finally, through the lightweight multi-objective optimization design of the modular and multi-cell structure bus body, with its structural strength, stiffness and rollover safety design requirements under the premise, realize the goal of losing weight 277 kg, 10.6% of the whole bus weight.